1. Field of the Invention
The present invention relates to a water-cooled internal combustion engine.
2. Description of Background Art
As described in e.g. Japanese Patent Laid-open No. 2004-036584, a water pump for circulating cooling water in a water-cooled internal combustion engine is mounted to a crankcase cover or the like.
The water pump described in Japanese Patent Laid-open No. 2004-036584 is configured such that a pump drive shaft parallel to a crankshaft is journaled by a pump body formed to be included in a crankcase cover and rotation of the crankshaft is transmitted to the pump drive shaft via a chain.
Thus, if the main body of then internal combustion engine is applied to an air-cooled engine, the crankcase cover should be replaced. In addition, the crankcase cover, which is a large-sized component with a various functions, cannot be shared even by the air-cooled engines with the result that the change of the cooling system becomes ambitious to thereby increase costs.
Incidentally, a water pump is mounted to a crankcase in some cases; however, it is difficult to replace the crankcase particularly. The change of a cooling system becomes increasingly ambitious to thereby further increase the costs.